In the past, heavy duty mechanical and/or hydraulic closing devices were utilized with the retread molds during the formation of a new tread in retreading material on radial tire carcasses. The use of such closing devices required apparatus that is extremely heavy and expensive. Further, tire distortion frequently occurs when the molds are closed on the tire. This was particularly true if the tires were slightly large in diameter. In such cases, the tire would often buckle and thus could no longer be used.
Another method of recapping or retreading tires is illustrated in U.S. Pat. No. 4,767,480 issued Aug. 30, 1988 to Leon C. Goldstein. In that patent, there is described apparatus and method for recapping or retreading that uses a cold process. In that process, a flexible tread mold is utilized that is stretched over the tire carcass. Subsequently, an envelope is placed over the mold and tire assembly and the entire unit is placed in a chamber where curing of the rubber is accomplished by inflation of the tire carcass, evacuation of the envelope and pressurization of the chamber and the application of heat.
U.S. Pat. No. 5,053,094 issued Oct. 1, 1991 to Richard H. Detwiler illustrates a method of retreading a tire wherein an uncured rubber layer is placed between the tire carcass and the undersurface of a precured tread layer held in place by prestressed bands that are constructed from a synthetic polymer. The bands are tensioned to exert a force on the precured tread layer so that the tread layer is adhered to the carcass by the uncured rubber as it cures in a curing chamber.
U.S. Pat. No. 4,588,460 issued May 13, 1986 to Arthur W. McGee, et al. illustrates a method and apparatus for retreading a tire that includes a relatively flexible mold that may be formed of a plurality of segments. The ends of adjacent mold segments may include guides so that the mold, when closed, will form a circle about the tire to be retreaded. In this process, an elastic band may encircle the segmented mold for the purpose of holding the mold in position on the tire during handling such as when the envelope is placed over the tire which ultimately is pressurized to force the mold segments into the uncured rubber tread material encircling the tire.